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March 8, 1932.

C. T. THORSSELL Filed July 5, 1950 r y 0 U mrrem M www Wwwwm .mbvfo sham Patented Mar. 8, 1932v L v uN-Ijrsn; sTAfrEs era CARL THEODQR THoRssELL, or'onssnt, GERMANY I PRocEss non THE rnonnorrou or roressrnM nrrisririal AND sonruM'- onniaonnil-1n application :nea Julie, 1930, sriaino.

u One known method of producing potassium vnitrate isfthe decomposition of potassium suf1phate by means of calcium nitrate 1 'KzSOl-Ca(NQg)22KNOgl-CaSO4 The gypsum/formed is separated fromr the potassium nitrate solution by; decantation or filtration and thepotassiumr nitrate solu tion so obtainedis evaporated.

lo `This' method ofmakingpotassiumnitrate appears very simple and promising, buty se` 'rious obstacles stand 1n-j1tsWay. n 1

In the irst place the reaction does'not'proceed so simply as is to be assumed from the l above equation, since' not' only gypsum butV double Vcompoundsl of potassium vand calcium with sulphuric acid also are formed, suchl as sjyngenite, (I{2SO4.CaSO.H2O) andpotas- As a result of this there is loss of potassium -which renders the process Ymore expensive and makes it less proitable5`or unproiitable. 5 A further obstacleis that potassium sulphate is in itself a too valuable raw material `for the manufacture of potassium nitrate, more particularly if thepotassium nitrate is to be used as a fertilizer.; v f v The invention describes a process .which enables the, above reactionV tobe used for the production of potassiumvgnitrate without he said disadvantagesobtaining. n l patent application vSer., No. 481,336 a 35 process is described by means of whichfpotassium sulphate and sodium carbonatefare made from sylvinite, in which gypsum is stirred into the sodamother-liquor and va liquor containing ammonium sulphate is vobf tained VVwhich is usedor working up the sylvinite to potassium sulphate;l During the stirring of the gypsum-inthe sodium bicarbonate mother-liquor calcium carbonate is obtained as ahy-productwhich must fbe removed from the process, l v t is provided in the second patentclaim of the same application that if the potassium sulphate vobtained is used for af process in which calcium'sulphate isproduced, the latter is introduced into the process again In ried outas follows:

465,794, andra eer-many Julyla, 1929.

this way the sulphuric acid in the process remains in circulation soV that there is no conl sumption ofthis acid." 1' VIn the 4present invention'not onlyis the sul- Y i* p'huric acid'maintained in .c irculatiombut A5.5

the' calcium also', the .calcium fcarbon'ate, 'which is otherwise, thrown ontoA the waste heap, being led back into-the process and combined vagain Vwith sulphuricf acid to form gypsum which-servesto prepare fresh quanti ties of potassium sulphate for stirring intoV thel soda mother-liquor. v The processV is car- Gypsum is stirred into the mother-liquor of an ammonia-sodium carbonate process the sfo-g. called Solvay process, it reacts with the ammonium carbonate and ammonium biecar'- bonate present in the liquor to form ammonin um sulphate andv calcium carbonate oasoiwum) 2co3: (NH4) iso*4 maso;V

The latteris separated ofi' andthey liquor ,is stirred upwith sylvinite, ammonia being led in at they same time. In this way sodium potassium sulfateor .glaseritefand potassium chloride formas a precipitate which,fafter separa-tion from the liquonis treated withV water whereby potassium sulphate vand a solutionofsodium chloride areformed SKClPQNaCHfMNHQZSOi-*f t the mother-liquor from the Solvay process 1i;

with gypsum is decomposed with the potassium sulphate obtained in a later stage of the process and nitric acid, whereby potassium nitrate and gypsum are formed.

K2SO4+ QHNOS -l- CaCO3 CaSOfl- QKNO3 -l- CO2 -l-HgO.

The potassium nitrate goes into solution, and after separation of the gypsum, is obtained by evaporation or cooling. The gypsum separated od is stirred into the mother' stacles hindering the same, i. e. loss of po-V tassium in the gypsum separating out and the use of the expensive potassium sulphate as raw material being eliminated.

Sylvinite, nitric acid, carbonio acid and ammonia serve as raw materials, and potassium nitrate, sodium carbonate and ammonium chloride are obtained as products. The ammonia may also be dispensed with as a raw material, if this is desirable, through recovery of the same by expulsion from the ammonium chloride, just as is generally usual in the manufacture of soda sodium carbonate, in which case therefore only potassium nitrate and soda are obtained.

Reference is here made to the attached flow sheet:

Sylvinite (KOH-NaCl) is stirred up in vessel a with a liquor consistingchiefiy of (NHQQSO and NH4C1 and ammonia is introduced. Glaserite is formed which is very diiiicultly soluble in the ammoniacal liquid.

In the solid substance, which is filtered off in the filtering apparatus b, there is contained in addition to glaserite that quantity of KCl which has been removed from NaCl during the. formation of glaserite because the quantity of crude salt is so selected that the KCl contained there-in is equivalent to the quantity of SO4 in the solution.

This solid substance is stirred up with water in vessel c, the following reaction taking place:

Consequently, the solid substance separated in the filtering apparatus CZ consists of K2S04 and the solutionV which is returned to the process consists of NaCl.

The K2SO4, which is thereby obtained, is

solved into HNO3 in vessel e whereupon KNO?` and CaSO4 are formed.

Kgsocacogafennos:

2KNo3+caso,+H2o+co2.

The CaSOil, which is formed, is filtered off in filter f and the KNO3 solution is led to the evaporator g in order to obtain KNO3 as the final product.

The solution obtained from the filtering apparatus b and chiefly containing NaCl, NHiCl and NH3 is neutralized with CO2 in vessel h and cooled in vessel i thereby precipitatingNHiCl. y

rThe second final product isr NILCl which is filtered off in the filtering apparatus 7c.

The liquor is treated with NH3,v and CQ2 in vessel VZ according to the ammonia-sodiumcarbonate process, Solvay process, and further worked into sodiumcarbonate which constitutes the third final product.'

The CaSOi which is filtered olf in jf is stirred with the final liquor in m obtained by the ammonia-sodium-carbonate process, Solvay process, whereupon CaCOa and (NI-14,)2S04 are formed.

oasoffanrnricof Y i i y ,cacomL (Nnazsoffngo-tooz.

The CaC'Os *isV either separated in filter fn, and treated per se-as described above-with K2SO4 and HNOS or it is left in the solution and mixed with the K2SO4 it then undergoes the said treatment. y

The CO2 which is liberated in Vessels e and lmI returns to the process. Moreover, lacking CO2 must be added.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, l declare that what I claim is l. A process for the production of potasy sium nitrate and'sodium carbonate, consisting in stirring sodium bicarbonate mother liquor obtained in the process with gypsum also obtained in the process, separating the calcium carbonate formed, treating the remaining liquor with crude sylvinitic potassium salt and ammonia, separating the precipitate of glaserite and potassiumv chloride formed from the liquor, treating the said precipitate with water to obtain potassium sulphate, treating the said potassium sulphate with calcium carbonate obtained in the process and nitric acid, thus obtaining gypsum and a solution of potassium nitrate, cooling the liquor remaining after the separation of 'the precipitate of glaserite and potassium chloride, to remove a portion of the ammonium chloride contained therein, subjecting the resulting liquor to the Solvay process, and stirringY the mother liquor obtained thereby p Y1,s4e,"'ns

with the gypsum olotained in theproductionp of potassium nitrate, as set forth. v

2. A process as Claimed in claim 1 and in which the greater part of the potassium nitrate is separated out in solid Vform from the potassium nitrate liquorrby cooling, and the mother liquor is used forthedissolving'of further quantities of potassium sulphate .for decomposition with Vnitric Vacid and calcium carbonate. In testimony whereof I have name to this specifleation., A: Y

CARL THEODOR THORSSELL signed 

